1. Field of the Invention
The present invention relates generally to stepper motor drive circuits. More specifically, the present invention relates to stepper motor stall detection.
2. Description of the Related Art
Instrumentation devices must be carefully designed with regard to accuracy. An ultimate requirement for such devices based on stepper motors is to preset the rotor of the stepper motor into a known position (zero position) at system start up time. Zero positioning typically involves stepper motor stall detection which occurs when the motor's rotor is prevented from rotation by some mechanical obstacle.
Methods for stall detection may be sensor-based, or sensorless and based on monitoring different phenomena occurring in the motor during stall. Since stepper motors are controlled in the open loop, loss of synchronization caused by a mechanical failure, vibration, temperature drift, and so forth, may cause cumulative errors, and as a consequence, incorrect instrument readings. These same variable factors pose a significant challenge to accurate zero positioning.